JP2003107943A - Fixing device and image forming device equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce failure that recording paper is wrinkled in a fixing device for fixing a toner image on the recording paper. SOLUTION: This fixing device 14 for fixing the toner image transferred to the recording paper is equipped with a 1st roller 111 whose shaft position is fixed, a 2nd roller 121 capable of moving in a contacting/separating direction with respect to the roller 111 and energized to the roller 111 by a spring 151, and an advancing guide member 141 for guiding the recording paper to a nip part 31 between the rollers 111 and 121, and the shaft 121c of the roller 121 and the member 141 are fixed on a 2nd roller frame 125, so that they are interlocked and moved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device incorporated in an image forming apparatus such as a copying machine, a printer, and a FAX, and an image forming apparatus provided with the fixing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a fixing device for fixing a toner image transferred on a recording sheet has been used. In a general fixing device, the pressure roller is pressed against the heating roller, and the recording paper on which the toner image is transferred is sent to the nip portion between the heating roller and the pressure roller to fix the toner image. It is supposed to be done. A guide member for guiding the recording paper to the nip portion is provided at the recording paper carry-in port of the fixing device.

[0003]

However, in such a fixing device, the heating roller and the pressure roller are affected by a change in the quality and thickness of the recording paper, or the surface of the roller is scraped or deformed due to long-term use. May change the relative positional relationship (the distance between the shafts of the two rollers) with each other, which may change the position of the nip portion. In such a case, the recording paper fed to the fixing device is not normally conveyed to the nip portion by the guide member, and there is a possibility that the recording paper is jammed, or the recording paper is wrinkled.

In view of the above circumstances, the present invention provides a fixing device capable of reliably guiding the recording paper fed into the fixing device to the nip portion and performing an appropriate fixing process.

[0005]

According to a first aspect of the present invention, in a fixing device for fixing a toner image transferred on a recording sheet, a first roller having a fixed axial position and a contact / separation direction with respect to the first roller. A second roller that is movable toward the first roller and is biased toward the first roller; and an entrance guide member that guides the recording paper to a nip portion between the first roller and the second roller, The fixing device is characterized in that the shaft of the second roller and the entrance guide member move in conjunction with each other.

In this way, the shaft of the second roller and the entrance guide member move in conjunction with each other, and the relative positional relationship between the shaft of the second roller and the entrance guide member is always kept constant, which results in a long time. Even if the axial position of the second roller moves relative to the first roller due to deformation of the roller due to use and the nip portion moves, the relative positional relationship between the nip portion and the entrance guide member is always kept substantially constant. You can Therefore, it is possible to always guide the recording paper fed to the fixing device normally to the nip portion from the entrance guide member, and reduce the risk of problems such as jamming of the recording paper and wrinkling of the recording paper.

According to a second aspect of the invention, in the fixing device according to the first aspect, the entrance guide member is attached to a second roller frame on which the shaft of the second roller is rotatably supported. It is a device.

With this structure, the shaft of the second roller and the entry guide member are attached to the second roller frame, and thus are attached to the same member. The positional relationship between the roller shaft and the entrance guide member can be maintained.

According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the force for urging the second roller can be adjusted.

With this configuration, an appropriate nip pressure can be applied according to the thickness and quality of the recording paper and the type of image such as a monochrome image and a color image. Even in this case, the nip portion and the entrance guide are always provided. The relative positional relationship of the members can be kept substantially constant, and the recording paper can be surely guided to the nip portion to perform proper fixing processing.

Further, according to the image forming apparatus having the fixing device as described above, it is possible to reduce problems such as jamming of the recording paper and wrinkling of the recording paper.

[0012]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIGS. However, the present invention is not limited to the following embodiments.

FIG. 1 is a schematic diagram showing a schematic configuration of an image forming apparatus according to the present invention. As shown in FIG. 1, in a printer (an example of an image forming apparatus) 1, a developing device 3 is provided in a printer body 2 for each color of black, cyan, magenta, and yellow. Each developing device 3
Is provided with a photoconductor drum 4 and is adapted to rotate in the direction of the arrow in the figure. This photosensitive drum 4 is a charging unit 5.
LED light based on image data input from an external PC or the like is uniformly radiated by the exposure unit (LED print head unit) 6 onto the drum surface to form an electrostatic latent image. Toner is supplied to the latent image to form a toner image. The toner is supplied from the toner supply containers 7M, 7C, 7Y and 7B. A recording paper conveyance belt 8 is arranged below the four photoconductor drums 4 arranged in parallel for each color. The recording paper conveyance belt 8 is pressed against each photoconductor drum 4 by the pressure roller 9, and is rotated by the rollers 10 and 11 in the forward direction of the rotation direction of the photoconductor drum 4.

Then, the recording paper is conveyed between the photosensitive drum 4 and the recording paper conveying belt 8 from the paper feeding mechanism 12 through the recording paper conveying path 13, and the recording paper is of each color.
While being conveyed between the recording paper conveyance belt 8 and the recording paper conveyance belt 8, the toner images of the respective colors on the surface of the photosensitive drums 4 are successively transferred to the recording paper by the transfer bias. The recording paper on which the toner images have been transferred from all the photoconductor drums 4 is conveyed to a fixing device 14 having a fixing roller pair, where the toner images are heat-fixed at a nip formed by the fixing roller pairs to form a color image. The recording paper that has passed through the fixing device 14 is the recording paper conveyance path 1
5, and is discharged from the discharge unit 16.

Each of the above-mentioned photosensitive drums 4 is provided with a cleaning mechanism 20 for removing residual toner and the like on the photosensitive drums 4. The cleaning mechanism 20 includes a cleaning roller 21 and a cleaning blade 22 for cleaning the surface of the photosensitive drum 4, and the cleaning roller 21 and the cleaning blade 2.
It has a spiral 23 for collecting the toner removed from the drum surface by 2 in one place.

FIG. 2 is a sectional view of the fixing device 14 as seen from the front. Although the left half is not shown in this figure, the right half has exactly the same structure, and is omitted in this description.

The fixing device 14 is provided with a fixing device frame 101 which forms the outer shape of the fixing device 14.

The fixing device frame 101 has a side surface 101a.
And a coupling portion mounting portion 101b protruding inward from the side surface portion 101a. A bearing 113 is fixed to a hole provided in the side surface portion 101a, and the shaft portion 111c of the first roller 111 is fitted into the hole in the bearing 113, so that the first roller 111 has its axial position relative to the fixing frame 101. Is fixed. Further, the spring 1 is attached to the connecting portion attaching portion 101b.
The second roller frame 125, to which the second roller 121 is attached, is connected via the coupling portion 150 including 51.

The first roller 111 is a heating roller having a heat generating portion (not shown) therein, and as shown in FIG. 3, a roller base portion 111a, a coating portion 111b covering the roller base portion 111a, and a shaft. And a portion 111c.

The roller base 111a is made of a material having a heat transfer property, for example, a metal material or the like, and particularly preferably an aluminum material having a high heat transfer property, a low density and a light weight.

The covering portion 111b is made of, for example, silicone rubber or the like having elasticity and excellent heat resistance. Particularly, the surface of the covering portion 111b is made of a fluororesin to improve abrasion resistance and the like. It is preferable to configure.

The second roller frame 125 has a side surface portion 12.
5a, and an upper surface portion 125b and a bottom surface portion 125c that are coupled to the upper and lower portions of the side surface portion 125a. Side part 12
The bearing 123 is fixed to the hole provided in 5a, and the shaft portion 121c of the second roller 121 is fitted into the bearing 123, so that the second roller 121 is fixed to the second roller frame 125.
Its axial position is fixed with respect to.

The second roller 121 is a pressure roller that is urged and pressed toward the first roller 111, as will be described later. Between the first roller 111 and the second roller 121, these two rollers are provided. A nip portion 131 is formed to function as a pair of fixing rollers.

As shown in FIG. 3, the second roller 121 has a roller base portion 121a, similar to the first roller 111.
It has a covering portion 121b and a shaft portion 121c.

The roller base portion 121a and the covering portion 121b are
Although it is possible to use a material that is substantially the same as that of the first roller 111, when forming a color toner image on the recording paper, the covering portion 121b of the second roller 121 is made of a material softer than that of the first roller 111. It is preferable to fix a clear image. Further, in order to more efficiently heat the recording paper introduced into the nip portion 131, a heat generating portion may be provided inside the roller base portion 121a.

The second roller frame 125 to which the second roller 121 is attached in this manner is connected to the fixing device frame 101 via the connecting portion 150 on the upper surface 125b.

The connecting portion 150 includes a pressure bolt 153 penetrating through holes provided in the upper surface portion 125b of the second roller frame and the connecting portion mounting portion 101b of the fixing roller frame 101, and the connecting portion mounting portion 101b. The pressure nut 155 and the pressure bolt 153 screwed into the pressure bolt 153 on the upper side are inserted, and the upper and lower ends thereof are on the lower surface of the upper surface 125b of the upper surface 125 of the second roller frame 125 and the lower portion of the pressure bolt 153. It is composed of a spring 151 pressed by a flange portion 153a provided.

According to the connecting portion 150, the second roller frame 125 is moved up and down by the pressure bolt 153.
That is, the second roller 121 is operable in the direction of connecting to the first roller 111. Also, the spring 15
1 is the second roller frame 125 and the fixing device frame 10
The second roller 121 fixed to the second roller frame 125 is biased so as to be pressed against the first roller 111 fixed to the fixing device frame 101 by pressing the first roller 111 upward. To be done.

The pressure nut 15 for the pressure bolt
By changing the screwing position of No. 5, the second roller 121
The force that urges the first roller 111 against the first roller 111 can be adjusted.

On the second roller frame 125, the recording paper conveyed to the fixing device 14 is nipped.
An entry guide member 141 for guiding to 31 is attached.

FIG. 3 is a side sectional view of the fixing device 14, FIG.
FIG. 3 is a perspective view of the fixing device 14.

As shown in these figures, the approach guide member 141 has an upper surface 125b of the second roller frame 125.
Is attached to the upper surface of.

The approach guide member 141 includes a fixed portion 141b located on the bottom surface, an upright portion 141c which is uprighted from both side surfaces of the fixed portion 141b, and a guide portion 141a which is installed on the upright portion 141c. And are fixed to each other by integral molding.

The guide part 141a has its upper surface extending from the lower part of the carry-in port 103 to the vicinity of the nip part 131 so that the recording paper conveyed from the carry-in port 103 to the fixing device 14 can be guided to the nip part 131. It is formed as a substantially flat climbing slope. The fixing portion 141b is fixed to the upper surface of the upper surface portion 125b of the second roller frame 125 with a bolt or the like (not shown).

The approach guide member 14 thus configured
1 is fixed on the upper surface portion 125b of the second roller frame 125, and therefore moves in conjunction with the second roller frame 125. Therefore, the shaft 121c of the second roller and the approach guide member 141 move in conjunction with each other.

In the fixing device 14 as described above, the conveyed recording paper is carried in from the carry-in port 103 and is guided to the nip portion 131 through the upper surface of the guide portion 141a of the entry guide member 141. After that, in the nip portion 131, the toner image is thermally fixed on the recording paper by the fixing roller pair of the first roller 111 and the second roller 121. The recording paper on which the toner image has been fixed is conveyed to the discharge guide portion 161, and discharged from the fixing device 14 via discharge rollers 163 and 163.

According to the above configuration, the shaft portion 121c of the second roller 121 and the entrance guide member 141 move in association with each other, and the relative positional relationship between the shaft portion 121c of the second roller 121 and the entrance guide member 141 is determined. Because it is always kept constant,
Even if the first roller 111 and the second roller 121 are deformed by the pressure applied to the fixing roller pair due to long-term use, the position of the shaft portion 121c of the second roller 121 moves with respect to the first roller 111. Even if the nip portion 131 moves, the relative positional relationship between the nip portion 131 and the entrance guide member 141 can always be kept substantially constant. Therefore, the recording paper sent to the fixing device 14 is always normally guided from the entrance guide member 141 to the nip portion 131. Therefore, it is possible to reduce the risk that the recording paper will be jammed, or the recording paper will be wrinkled.

Further, the shaft portion 121c of the second roller 121
Since the entry guide member 141 is attached to the second second roller frame 125, the positional relationship between the shaft portion of the second roller 121 and the entry guide member 141 can be reliably retained with a simple structure.

Further, by tightening or loosening the pressure nut 155, the spring 151 can adjust the force for urging the second roller frame 125 toward the fixing device frame 101. An appropriate nip pressure can be applied according to the paper thickness and paper quality, and the type of image such as a monochrome image and a color image. Even in this case, the relative positional relationship between the nip portion and the entrance guide member is always kept substantially constant, the recording paper can be reliably guided to the nip portion, and proper fixing processing can be performed. It is possible to reduce the possibility that the above problem will occur.

In the present embodiment, the first roller 111 and the second roller 121 are installed so as to face each other in the vertical direction, but they may be installed so as to face each other horizontally or diagonally. Good.

Further, the fixing device 14 according to the present embodiment.
Can be used for all image forming apparatuses provided with an image forming mechanism for forming a predetermined toner image and transferring the toner image on a recording sheet. For example, a copying machine, a fax machine, a printer, etc. may be mentioned.

[0042]

As is apparent from the above description,
According to the fixing device of the present invention, since the shaft of the second roller and the entrance guide member move in conjunction with each other, the relative positional relationship between the nip portion and the entrance guide member can always be kept substantially constant. Therefore, even if the movement of the nip portion occurs, the recording paper is normally guided from the entry guide member to the nip portion, and it is possible to reduce the possibility that a problem such as wrinkling of the recording paper occurs.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an image forming apparatus according to the present invention.

FIG. 2 is a sectional view of the fixing device according to the present invention as viewed from the front.

FIG. 3 is a cross-sectional view of a fixing device according to the present invention as seen from a side surface.

FIG. 4 is a perspective view of a fixing device according to the present invention.

[Explanation of symbols]

14 Fixing device 111 First roller 111c shaft 115 body frame 121 Second roller 121c shaft 125 second roller frame 131 Nip part 141 Entry guide member 141a guide part 141b fixed part 150 joint 151 spring 153 Pressure bolt 155 pressure nut

Claims (4)

[Claims] 1. A fixing device for fixing a toner image transferred onto a recording sheet, comprising: a first roller having a fixed shaft position;
A second roller that is biased toward the first roller, and an entrance guide member that guides the recording paper to a nip portion between the first roller and the second roller are provided. A fixing device in which a guide member moves in conjunction with each other. 2. The fixing device according to claim 1, wherein the entrance guide member is attached to a second roller frame on which a shaft of the second roller is rotatably supported. 3. The fixing device according to claim 1, wherein the force for urging the second roller can be adjusted. 4. The image forming apparatus according to claim 1, further comprising an image forming mechanism that forms a predetermined toner image and transfers the toner image onto a recording sheet. .